In a balloon catheter, a dilatable balloon is installed at a distal end portion thereof. For example, the balloon catheter is used in order to dilate a stenosed portion or an obstructive portion so as to improve blood flow when stenosis or obstruction occurs in a blood vessel. The balloon has been configured to have strength and shock resistance able to withstand an increase of internal pressure when a target portion is dilated.
However, there exists the possibility of breakage of a balloon caused by an unexpected rapid increase of internal pressure or a shock due to unexpected contact with biological tissue which is hardened, that is, calcified, for example. A rupture in a circumferential direction and a rupture in an axial direction are assumed when there is a breakage of the balloon. Different from the rupture in the axial direction, a fragment separated from the balloon is likely to occur in the rupture in the circumferential direction. Therefore, there is an increased need to prevent the rupture in the circumferential direction from occurring.